# Bar Charts

A **bar chart** is used to present categorical, quantitative or discrete data.

The information is presented on a coordinate axis. The values of the variable are represented on the horizontal axis and the absolute, relative or cumulative frequencies are represented on the vertical axis.

The data is represented by **bars** whose **height** is **proportional** to the **frequency**.

#### Example

A study has been conducted to determine the blood types of a class of 20 students. The results are as follows:

Blood Type | f_{i} |
---|---|

A | 6 |

B | 4 |

AB | 1 |

0 | 9 |

20 |

# Frequency Polygons

A **frequency polygon** is formed by joining the tips of the bars (the values of the frequencies) by line segments.

#### Example

The changes in the temperature on a particular day are represented by the following variations:

Hour | Temperature |
---|---|

6 | 7º |

9 | 12° |

12 | 14° |

15 | 11° |

18 | 12° |

21 | 10° |

24 | 8° |